<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* 获取焦点 只对于表单标签 */
        input:focus{
            outline-color: chartreuse;
        }
    </style>
</head>
<body>
    <form action="#">
        <p>请输入你的账号：<input type="text"></p>
        <p>请输入你的密码：<input type="text"></p>
    </form>
</body>
</html>